1. Field of the Invention
The present invention relates generally to a video display appliance, and more particularly to an apparatus for preventing image sticking of a video display appliance and a method thereof that can effectively prevent or remove the image sticking occurring during the display of an image on the video display appliance.
2. Description of the Related Art
A television receiver (TV), which is a kind of video display appliance, selects a broadcasting signal of a channel selected by a user among broadcasting signals transmitted from broadcasting stations, demodulates the selected channel broadcasting signal, and separates the demodulated broadcasting signal into video and audio signals. Then, the TV processes the video and audio signals, and outputs the video and audio signals through a display screen and a speaker, respectively.
Generally, TVs are classified into CRT (Cathode Ray Tube) TVs that have most widely been used, LCD (Liquid Crystal Display) TVs, PDP (Plasma Display Panel) TVs, etc., that have the characteristics of a high picture quality and large scale screen.
In particular, the PDP TV has a fairly small thickness in comparison to the existing CRT TV according to its structural characteristic, and has a superior luminance characteristic in comparison to the LCD TV. Additionally, the PDP TV has an excellent layout characteristic such as wall mounting, and thus has been spotlighted as the next-generation TV.
However, in the case of the LCD TV, if a specified still image is displayed on the display screen for a long time or if an image the aspect ratio of which has been converted from 16:9 to 4:3 is displayed on the display screen for a long time, a residual image, i.e., image sticking, remains on a boundary part of the screen for a considerable time. Meanwhile, in the case of the PDP TV, the cell deterioration occurs, and this may cause the TV to suffer fatal damage.
In most video display appliances, voltage inversion is provided by lines or by pixels, and this causes the voltage inversion to be separately provided by fields. In this case, some voltage difference is actually produced among common voltages, and this voltage difference and the external environments cause the image sticking and the deterioration of pixels to occur. Additionally, if a still image is displayed on the display screen for a long time, the image sticking or the pixel deterioration may occur.
In order to properly cope with the above-described phenomenon, as illustrated in FIG. 1, a method of slightly moving the whole image displayed on the screen for a predetermined period to an extent that the user cannot recognize such movement has been proposed and used. According to his method, the movement of the image may repeatedly be performed in the order of left→downward→right→upward to make a circle or in the order of left→right only.
According to the conventional image sticking prevention method, however, the image displayed on the large scale screen repeatedly moves in the order of left, downward, right and upward, a black display region having a width of about one centimeter and corresponding to a non-signal section appears on the right, upper, left or lower border part of the screen in order, and this causes the user inconvenience in viewing the TV.